The present invention relates to optical metrology systems and methods thereof and, more particularly, to a novel optical metrology system and usage thereof for the coordinated polarization of an illumination beam so that the polarization angle changes simultaneously as the sensor and/or the object to be scanned accomplishes the scan process.
In optical metrology, inter-reflection (i.e., double bounce or secondary reflection) poses a big challenge for surface measurement of shiny objects. Due to specular reflections that can occur among concave surfaces or combinations of surfaces positioned near right angles to each other, the true desired laser lines are often obscured by inter-reflection lines. Such obscuration makes it very difficult to measure shiny surfaces of complex surface geometry without first coating the surface with a highly diffusing material (e.g., a powder and the like) or without first deploying a part specific or laser line specific mask to block light to those regions that produce the secondary and/or specular reflections.
The coating of the surface to be scanned with a highly diffusing material so that there is no inter-reflection or the use of a mask to cover each individual area separately so that there is no inter-reflection adds a step to the scanning/inspection processes resulting in increased costs associated with the inspection process and an inspection process which is slower overall.
Accordingly, the need exists for an improved system and method for the measurement (i.e., scanning, inspecting, etc.) of relatively shiny surfaces.